Error in php foreach iteration - php

Question

I have this laravel collection called $articles_rows.
Collection {#320 ▼
#items: array:3 [▼
0 => array:6 [▼
"img_alt" => "<span>Original</span> gifts"
"class" => "personalised-gifts"
"elements" => array:2 [▼
0 => array:2 [▼
"id" => 2638
"type" => "ARTICLE"
]
1 => array:2 [▼
"id" => 2100
"type" => "ARTICLE"
]
]
]
1 => array:5 [▼
"img_alt" => "<span>Love</span> gifts"
"class" => "love-gifts"
"elements" => array:3 [▼
0 => array:2 [▼
"id" => 1072
"type" => "CATEGORY"
]
1 => array:2 [▼
"id" => 6186
"type" => "ARTICLE"
]
2 => array:2 [▼
"id" => 1028
"type" => "CATEGORY"
]
]
]
On the other hand, I have another collection called $cats_and_arts, this $cat_and_arts collection have extra information about the 'element' field in the $articles_rows collection.
This is my $cats_and_arts collection:
array:5 [▼
0 => {#313 ▼
+"type": "ARTICLE"
+"name": "Ceramic Mug"
+"resource_id": "2638"
+"seo": {#314 ▶}
}
1 => {#323 ▼
+"type": "CATEGORY"
+"name": "Personalised Blankets"
+"category": {#325 ▼
+"id": 1072
+"gallery_id": null
+"final": true
}
+"seo": {#326 ▶}
}
2 => {#327 ▼
+"type": "ARTICLE"
+"name": "Circle Cushion"
+"resource_id": "2100"
+"seo": {#328 ▶}
}
3 => {#329 ▼
+"type": "ARTICLE"
+"name": "Book"
+"resource_id": "6186"
+"seo": {#330 ▶}
}
4 => {#341 ▼
+"type": "CATEGORY"
+"name": "Gifts for men"
+"category": {#342 ▼
+"id": 1028
+"gallery_id": null
+"final": false
}
+"seo": {#343 ▶}
}
]
I want replace the $cats_and_arts CATEGORIES and ARTICLES by the $articles_rows elements field.
I want this final result:
Collection {#320 ▼
#items: array:3 [▼
0 => array:6 [▼
"img_alt" => "<span>Original</span> gifts"
"class" => "personalised-gifts"
"elements" => array:2 [▼
0 => {#313 ▼
+"type": "ARTICLE"
+"name": "Ceramic Mug"
+"resource_id": "2638"
+"seo": {#314 ▶}
}
2 => {#327 ▼
+"type": "ARTICLE"
+"name": "Circle Cushion"
+"resource_id": "2100"
+"seo": {#328 ▶}
}
]
]
1 => array:5 [▼
"img_alt" => "<span>Love</span> gifts"
"class" => "love-gifts"
"elements" => array:3 [▼
0 => {#323 ▼
+"type": "CATEGORY"
+"name": "Personalised Blankets"
+"category": {#325 ▼
+"id": 1072
+"gallery_id": null
+"final": true
}
+"seo": {#326 ▶}
}
1 => {#329 ▼
+"type": "ARTICLE"
+"name": "Book"
+"resource_id": "6186"
+"seo": {#330 ▶}
}
2 => {#341 ▼
+"type": "CATEGORY"
+"name": "Gifts for men"
+"category": {#342 ▼
+"id": 1028
+"gallery_id": null
+"final": false
}
+"seo": {#343 ▶}
}
]
]
And this is my code, but, return me an error
Undefined index:id in the line 'if($article_element['id'] ==
$extra_element->category->id)'
when the loop have more than one iteration:
foreach($articles_rows as &$article)
{
foreach($article['elements'] as &$article_element)
{
foreach($cats_and_arts as $extra_element)
{
if($extra_element->type == 'CATEGORY')
{
if($article_element['id'] == $extra_element->category->id)//Undefined index:id
{
$article_element = (array)$extra_element;
}
}
if($extra_element->type == 'ARTICLE')
{
if($article_element['id'] == $extra_element->article->id)
{
$article_element = (array)$extra_element;
}
}
}
}
}

Answer 1

When you reassign the value of $extra_element, you're "removing" the property id, which you are using in the if.
There are 2 solutions:
Keep the id in your object.
$article_element = array_merge((array)$extra_element, $article_element);
Modify your condition to make sure the property exists in your array.
if (array_key_exists('id', $article_element) && $article_element['id'] == $extra_element->category->id)

Answer 2

Your issue is coming from the use of an array reference iterator in:
foreach($article['elements'] as &$article_element) {...}
Because you later overwrite the entire array at $article_element, the foreach iteration cannot continue. This can probably be corrected by iterating with both a key and value and overwriting the array not by its iterator variable, but rather directly by its key in the parent array.
// Iterate the loop with a variable for the key
// instead of using a reference
foreach($article['elements'] as $key => $article_element)
{
foreach($cats_and_arts as $extra_element)
{
if($extra_element->type == 'CATEGORY')
{
if($article_element['id'] == $extra_element->category->id)//Undefined index:id
{
// Overwrite it by key in the parent array
$article['elements'][$key] = (array)$extra_element;
}
}
if($extra_element->type == 'ARTICLE')
{
if($article_element['id'] == $extra_element->article->id)
{
// And do the same here...
$article['elements'][$key] = (array)$extra_element;
}
}
}
}
Note: I didn't include the outermost loop here. It does not need modification as far as I can tell, although the array reference &$article is probably unnecessary. You may be able to use
foreach ($article_rows as $article) {...}
because I don't see anywhere that you modify that outer iterator.